袁河流域极端降水事件成因分析

利用欧洲中期天气预报中心格点再分析资料和HYSPLIT模式对袁河流域5次极端降水天气过程的平均环流背景、主要影响系统、物理量场以及降水发生过程中的120 h气块后向轨迹特征进行分析。结果发现:(1)极端降水发生时,高层袁河流域处于南亚高压东侧辐散气流中,中层副热带高压位置适中,受584 dagpm线附近的西南气流控制,低层正好处于切变线上,且有强盛的西南气流向降水区输送能量和水汽。(2)物理量场上,袁河流域附近低层辐合、高层辐散,垂直速度场、水汽分布、水汽通量散度场都有利于该区域出现暴雨天气。(3)与袁河流域一般性暴雨的平均t-lnp图对比分析可见,极端暴雨的能量条件更好,降水对流性更强,水汽条件也更为充沛。(4)袁河流域极端降水上空的水汽路径总体上可以归纳为5条。来源于孟加拉湾附近、中南半岛南部和云南南部的西南水汽路径最多,占轨迹总数的59.5%;其次是来源于我国南海的南方路径,主要位于1 500 m以下,占轨迹总数的15.0%。     

Humidity of the tropical lower stratosphere: Observations and analysis

The results of measurements of water-vapor vertical profiles in the upper troposphere and stratosphere on board a meteorological balloon with a FLASH-B optical fluorescent hygrometer (Russia) are presented. These data were obtained during two international field campaigns in West Africa (August 2006) and Central America (August 2007). Eleven high-resolution water-vapor vertical profiles measured in the course of these works make it possible to characterize the processes controlling humidity in the tropical tropopause region. Layers with increased humidity are detected in the lower stratosphere over West Africa to the level of the potential temperature 450 K. An analysis of satellite maps of the brightness temperature, balloon ozone measurements, and aerosol scattering, as well as trajectory modeling, display the relation between the observed layers with increased humidity and the phenomena of convective overshooting of the tropopause, as a result of which cold and ozone-depleted air penetrates into the lower stratosphere together with ice particles, which, rapidly sublimating, locally increase the water-vapor concentration. A comparison of the humidity data obtained in West Africa in 2006 and in Central America in 2007 reveals substantial distinctions in values and vertical structures of water vapor, both in the tropopause region and in the middle stratosphere.     

Estimation of water-vapor and ozone transport in the upper troposphere-lower stratosphere and fluxes through the tropopause during the field campaign at the Sodankyla station (Finland)

Processes of mass exchange through the tropopause at extratropical latitudes are studied. For this purpose, balloon data on ozone and water vapor obtained during the LAUTLOS field campaign were analyzed and a trajectory model was used to analyze the origin of air masses and to calculate fluxes through the tropopause. The results of observations and trajectory modeling showed that tropospheric air masses penetrated into the stratosphere by no more than ～2.5 km above the tropopause level during the campaign. Both tropospheric and stratospheric particles are present in this mixing layer. Backward trajectories showed that, at the anticyclone boundary, tropospheric air penetrates into the stratosphere in the form of fine fibrous structures (filaments). The fluxes through the tropopause were also quantitatively estimated by the Wei method with the use of forward and backward trajectories. The spatial structure of the fluxes through the tropopause coincides with the regions of the tropopause inclination and its folds. The absolute values of the fluxes calculated with the use of the Wei method decrease, depending on the length of trajectories at the expense of the filtering-out of a shallow reversible exchange. It is shown that the exchange depth can be controlled by both vertical fluxes in the troposphere and changes in the level of the tropopause itself. The use of isentropic and three-dimensional trajectories made it possible to estimate the contribution of nonadiabatic processes to the stratosphere-troposphere exchange.     

新疆冬春季强降水过程的水汽来源及输送特征分析

利用常规观测资料和6 h一次的NCEP 1°×1°再分析场资料对新疆2015年2月12—14日北疆暴雪过程和2015年5月17—21日南疆暴雨过程的环流形势和主要影响系统进行分析,并基于HYSPLIT模式模拟的后向轨迹分析强降水的水汽来源和输送特征。结果表明:1) 2次强降水过程均发生在高空低槽东移,低层有低涡,地面有锋面气旋,高空有辐散的天气背景下。2)冬季暴雪过程中,北疆水汽主要源自西亚和中亚地区。其中源自西亚地区的干气块下沉到近地面时从下垫面获得水汽,对强降雪的贡献最大;其次是起源于中亚西南部地区近地层的湿气块对强降雪的贡献。3)春季暴雨过程中,南疆的水汽主要来自中亚的哈萨克斯坦。其中来自哈萨克斯坦南部上空的干空气下沉到近地层时从下垫面获得水汽,对强降雨的贡献最大;其次是源自哈萨克斯坦东部和东南部对流层低层的湿气块对强降雨的贡献大。4) 2次强降水过程中水汽主要来自陆地而不是海洋,气块在近地层移动或下沉到近地层时,下垫面水汽蒸发使气块变湿,是强降水的水汽主要贡献者;表明春季和冬季的水汽输送通道与夏季来自阿拉伯海等低纬的水汽通道不同。     

A STUDY OF MOISTURE BUDGET OF A TYPHOON

This paper deals with the study of moisture budget of the typhoon No. 7507. The results show that the mass convergence produced by divergent wind has made the maximum contribution to precipitation, especially at the lower level, accounting for about 70% of the total precipitation, and that the advection term of water vapor is very small. The vertical flux term is to transport water vapor from the lower level to the middle and upper levels, resulting in the increase of water vapor accumulation at these levels. Evaporation term also plays an important role in precipitation, accounting for about 13% of the total precipitation and 23% of the horizontal moisture convergence. The moisture of the typhoon comes mainly from its southern boundary and the secondary inflow of moisture is from its western or eastern boundary. All the inflow layers of these three boundaries are very deep, reaching up to 300 hPa, while the strongest inflow occurs below 700 hPa. In the northern boundary of the typhoon, we obtained that     

Interannual variation of atmospheric mass and the southern oscillation

Two reanalysis datasets, one generated by the Goddard Laboratory for Atmospheres for 1982–1993 and the other generated by the National Centers for Environmental Prediction for 1982–1995, are used to examine the relationship between the Southern Oscillation (SO) and the interannual variation of atmospheric mass. Both reanalyses show that atmospheric mass increases (decreases) during the positive (negative) SO phase. Atmospheric mass consists of dry air and moisture. Since dry mass is conserved, the interannual variation of atmospheric mass results from the variation of water vapor pressure. Thus, global atmospheric hydrological processes are analyzed to illustrate how the SO affects the interannual variation of atmospheric mass. During the positive (negative) SO phase, water vapor is converged (diverged) toward (out of) the central-eastern tropical Pacific [where sea surface temperatures (SSTs) are higher (lower) than normal] to maintain (suppress) cumulus convection in that area. An anomalous east-west Walker circulation straddling the Dateline is driven by the anomalous cumulus convection in this region to create positive (negative) surface pressure anomalies over the western tropical Pacific-Indian Ocean, which result in an increase (decrease) in atmospheric mass.     

Retrieval of spatial field of atmospheric aerosol concentration according to data from local measurements: A modification of the method of back trajectory statistics

The well-known method of the back trajectory statistics (BTS) is used to develop a new approach to estimating atmospheric pollution fields according to local measurements. On the basis of instrumental measurements at one or a few monitoring points and information on atmospheric dynamics (in this work, back trajectories of the motion of air particles), the BTS method makes it possible to estimate the spatial structure of fields of a measured quantity. Results from solving a simplified demonstration of estimating the spatial distribution of the volume concentration of a fine aerosol fraction are presented; these results were obtained on the basis of an analysis of photometric measurements in the period of 2004–2010 at six AERO-NET monitoring sites on the territory of Russia: Zvenigorod, Moscow, Yekaterinburg, Tomsk, Yakutsk, and Ussuriisk.     

Filter-based differential hygroscopicity analyzer of aerosol particles

We describe a new differential analyzer implementing a technique for studying the hygroscopic properties of filter-precipitated aerosol particles based on a katharometric measurement of the amount of water vapor absorbed by an aerosol sample. The instrument has been tested on particles of sodium chloride and ammonium sulphate. A comparison of our data with the results of analogous measurements described in literature shows that the suggested technique has several important advantages, i.e., (1) higher sensitivity, which allows the measurement of particles of no more than 0.1 mg in mass; (2) a wide range of relative humidity variations (up to 99% at an accuracy of 0.06% RH at the upper-range value); (3) the absence of intermediate measurement steps connected with the need to account for water absorption by elements of a measurement system; and (4) the absence of restrictions to the size and shape of particles studied. In addition, the measurement technique rules out the possibility of errors caused by the kinetic effects of mass transport in the aerosol-water vapor system.     

Atmospheric correction of Landsat data for the retrieval of sea surface temperature in coastal waters

1IntroductionRemote sensingis an effective approach for esti-mation of the sea surface temperature(SST),andadvanced very high resolution radiometer(AVHRR)and moderate resolution imaging spectroradiometer(MODIS)thermal infared(TIR)data are widelyused in th…     

Estimate for radiative forcing of smoke aerosol from 2010 summer fires based on measurements in the Moscow region

Temperature and radiation effects of the 2010 summer fires are estimated on the basis of measurements at the Zvenigorod Scientific Station (ZSS) of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (RAS), in the Moscow region. The surface air temperature during the 2010 summer smoke varied in antiphase with the aerosol mass concentration, and the thermal radiation balance in the surface layer of the atmosphere varied in phase. Under extreme smoke of the surface layer in August 2010, the reduction in surface air temperature at ZSS has been found to reach 4 K with an increase in the downward flux of thermal radiation by an average of 20 W/m² and a decrease in the difference between upward and downward fluxes of thermal radiation by an average of 24 W/m².     

利用Landsat数据反演近岸海水表层温度的大气校正算法

介绍了一种将大气效应考虑在内、利用Landsat TM、ETM+热红外数据进行近海岸海表水温反演的单窗算法.在该算法中,将地表气温、相对湿度等常规气象资料作为初始参数,根据对流层中大气温度随高度呈线性降低、水汽随高度呈指数衰减的规律,建立了估算平均大气温度及水汽含量的通用模式.通过与实测数据及MODIS Terra海表水温产品比较发现,该算法能够提高运用TM/ETM+TIR单波段数据进行近岸海表水温(SST)反演的精度:一方面,反演所得结果更接近于海表实际水温;另一方面,它在一定程度上剔除大气中的水汽对SST反演的影响,进而提高海表水温的温度对比度.该提出的大气校正算法只需地表大气温度及相对湿度资料,该算法也无需进行大气模式的界定.     

Distribution of maximum water levels due to the Japan Sea Tsunami on 26 May 1983

By measuring the maximum water level of the traces attained by the Japan Sea Tsunami on 26 May 1983, we obtained the distribution along the west coast of the northeast Japan. The level reaches a maximum at the coast eastward of the epicenter and decreases with the relationship 8.6e ^–0.017x (m) with distancex (km) measured from the coast nearest to the epicenter. A small increase of levels was observed at coasts to the south of the tsunami source having distance larger than 200 km. With the aid of tide gauge records we revealed an excitation of edge wave which brought about the small increase of levels at the southern coast. In comparison with the decrease with distance obtained on the coasts of the main islands of Japan, some noticeable peaks were observed at several small islands. It is suggested that the reason why a short period component is predominant for the initial wave motion of tsunami is that the source region has depth of 3, 000 meters. The feature of wave period is discussed in comparison with that of the 1964 Niigata Tsunami.     

Analysis of prestorm situations in the Florida Straight and Golubaya Bay in the Black Sea

We consider some peculiarities of the behavior of thermal and radio thermal (microwave radiation) characteristics of the atmosphere during prestorm situations in water areas monitored directly and remotely. The objects of research are (a) a region of the SMKF1 station (Sombrero Key) in the Florida Straight in August 2005 and (b) Golubaya Bay in the Black Sea (Gelendzhik, the territory of the Southern Branch of the Shirshov Institute of Oceanology, Russian Academy of Sciences) in September 2010, several days before an intensive storm. Using meteorological and satellite microwave radiometric data, we have studied some common and specific features in the behavior of surface air temperature and humidity, surface fluxes of sensible and latent heat, total heat and water vapor content of the atmosphere, and microwave radiation characteristics of the “water surface-atmosphere” system during time periods preceding the approach of Hurricane Katrina to the region of SMKF1 and development of the sea storm near the Golubaya Bay. In both cases the effect of the accumulation of the latent heat of water vapor in the atmosphere was observed during the prestorm periods (of several days).     

Atmospheric transport of anthropogenic heavy metals from the Kola Peninsula to the surfaces of the White and Barents seas

The propagation of air masses and anthropogenic aerosol pollutants from a large industrial region located above the polar circle in the north of the Kola Peninsula is analyzed. The initial data are five-day-traveltime trajectories of air mass transport from the source, which were calculated for each day of January, April, July, and October over a period of 20 years from 1981 to 2000 according to the NOAA reanalysis data on meteorological fields. Seasonal and long-term variations in the mean concentrations of arsenic and heavy metals (Ni, Cu, Pb, Cd, V) in the surface air layer and precipitation over the waters of the White and Barents seas are studied. The results are compared with the published observational data characteristic of the region under study. It is shown that, on the whole, over a year, the atmospheric flux of persistent ecotoxicants from the Kola Peninsula to the waters of the White and Barents seas is fully comparable to the contribution of their inflowing rivers and this flux is dominant for nickel and copper.     

Evaluation of chemical ozone loss in the stratosphere over the Kola Peninsula in the 2002/2003 winter from microwave sounding data

From long-term observations of ozone evolution in the stratosphere of the Kola Peninsula in the 2002/2003 winter, the rates of chemical destruction of ozone and its net loss at isentropic levels of 530 K (an altitude of about 22 km) and 465 K (an altitude of about 19 km) ar evaluated with consideration for diabatic descent of air masses. These rates were ?18.6±3.3 and ?14.3±2.9 ppb/day and the net loss of ozone due to its chemical destruction over the period from December 1, 2002, to March 5, 2003, reached 1.77±0.33 ppm and 1.36±0.29 ppm, respectively. At the lower level, these data are in satisfactory agreement (to within measurement errors) with other measurements that were taken at that time. At a potential-temperature level of 530 K, the ozone loss in the 2002/2003 season evaluated from our data and from similar microwave measurements performed in Kiruna (Sweden) virtually coincides and testifies to the fact that the net loss increases with altitude. These inferences are inconsistent with the results obtained with the Match technique and the method of averaging over a vortex, which indicate that the ozone loss decreases with altitude. However, since polar stratospheric clouds were detected regularly in December and early January at levels up to 600 K or higher, it may be suggested that the ozone loss at these altitudes can be comparable to the values found for isentropic levels of 465 to 475 K.     

Large-scale turbulence under a solitary wave: Part 2: Forms and evolution of coherent structures

The instantaneous turbulent velocity field produced by a broken solitary wave propagating on a 1 in 50 plane slope was measured in the longitudinal transverse plane in the middle part of the water column and near the bottom using a stereoscopic particle image velocimetry system. These measurements showed that large-scale turbulence first arrived in the form of a downburst of turbulent fluid. In the middle of the water column, the downbursts arrived shortly after the wave crest had passed. Each downburst was accompanied by two counter-rotating vortices. The latter grew rapidly in size to become a prominent feature of the flow field. Each vortex had a typical length scale of 1/2 to 1 water depth, and carried most of the turbulent kinetic energy in the region between the vortices. Near the bottom, the counter-rotating vortices were not as well defined and covered only a small plane area compared to the entire flow structure. The turbulent fluid descending from above diverged at the bed and the resulting flow structure developed an elongated shape as the source of down-flow travelled onshore with the broken wave. It was found that the transverse spacing between adjacent downbursts ranged from 2 to 5 times the local still water depth. Since vortices cannot end in the interior of the fluid, the counter-rotating vortices must extend to the free surface in the form of a vortex loop. It was suggested that these vortex loops were produced by bending and stretching of primary vorticity generated in the wave breaking process, possibly as a result of three-dimensional water surface deformation. The vortex loops were then carried downward by the falling water from the broken wave.     

A very deep ozone minihole in the Northern Hemisphere stratosphere at mid‐latitudes during the winter of 2000

Ozone miniholes appear on total ozone maps as localized ozone minima with horizontal extents of a few hundreds of kilometres. They are characterized by a rapid and small‐scale appearance of a columnar ozone decrease with an equally rapid recovery after a few days. They are frequently observed at Northern Hemisphere mid‐latitudes in winter. Evolving too rapidly to be the result of an ozone chemical destruction, miniholes should be the result of meteorological processes. According to some authors, miniholes should be due to the northeast motions of air patches with low total ozone content. However, several studies attribute the formation of ozone miniholes to the uplift of air masses, which decreases the ozone columnar content by simply decreasing the pressure thickness of the ozone layer, without changing the mixing ratio. According to these studies, the latter mechanism explains the main reduction of ozone that occurs between the tropopause and the ozone maximum during an ozone minihole event. A region of extreme low ozone values passed over Europe from 27 to 30 November 2000. The total ozone values were measured with the Total Ozone Mapping Spectrometer (TOMS). A radio sounding, launched on 29 November 2000 from Payerne at the place and time of the deepening of the minihole, allows us to perform a detailed analysis of its formation mechanism. It is shown that the uplift of isentropic surfaces plays an important role in the columnar ozone decrease and explains the lower part of the depleted ozone profile. However, the deepening of the minihole is explained by another mechanism: namely, at this time the minihole air column intersects the polar vortex at high altitudes and then encounters ozone‐poor air masses.     

The Increase of Biogenic Sulfate Aerosol and Particle Number in Marine Atmosphere over the Northwestern North Pacific

During a cruise aboard the R/V Hakuho-maru in the northwestern North Pacific in the summer of 1998 the particle number concentrations and the major ionic components of size fractionated aerosols were measured to investigate the aerosol produced by marine biological activity. Continuous low concentrations of nitrate (<1.8 nmol m⁻³), similar to the marine air background level, were found over the northwestern North Pacific (40–45°N) and the Sea of Okhotsk (44–45°N). Over the Sea of Okhotsk, a high concentration of chlorophyll-a (5.4 mg m⁻³) in seawater was observed, and atmospheric concentrations of non sea-salt (nss-) sulfate (44 nmol m⁻³), methane sulfonic acid (MSA) (1.8 nmol m⁻³) and particle number in the size range of 0.1 < D < 0.5 μm (199 cm⁻³) were found to be 9, 7, and 2 times, respectively, higher than those in the background marine air. The increase in particle number concentrations mainly in the size range of 0.2 < D < 0.3 μm was likely caused by the increase of biogenic sulfate over the high productive region of the Sea of Okhotsk. In humid air conditions (R.H. > 96%), the increased biogenic sulfate that condensed the large amount of water vapor would not have sufficient solute mass to activate as cloud condensation nuclei (CNN) and would remain as aerosol particles in the marine air with frequent sea-fogs over the high productive region. Biogenic sulfate originating from dimethyl sulfide (DMS) would gradually grow into the CCN size and continuously supply a great number of CCN to the marine air in the northwestern North Pacific. This revised version was published online in July 2006 with corrections to the Cover Date.     

相似路径台风“摩羯”（1814）和“温比亚”（1818）影响南通降水差异成因分析

为探讨相似路径台风“摩羯”（1814）和“温比亚”（1818）影响南通降水的差异原因,从天气形势、物理量场等方面进行分析,利用水汽通量、假相当位温、湿位涡、垂直螺旋度等物理量对降水进行诊断,得到以下主要结论：1）两台风移动路径主要受副热带高压和冷空气的影响,副热带高压边缘气流为主要引导气流。两台风均有追随200 hPa辐散中心移动的趋势。2）较强冷空气的侵入、鞍形场中的缓慢移动、强正涡度和强盛上升运动、强水汽输送且低空长时间水汽辐合、大气斜压性增强和风垂直切变增大均是台风“温比亚”造成南通更强降水的原因。3）水汽通量辐合增强,低层正涡度中心、强上升运动,低层假相当位温大值区叠加上空假相当位温梯度带,垂直螺旋度增大与正值发展高度均与台风强降水有明显对应。     

湄洲湾海雾的发生规律和成因分析

利用湄洲湾及近海3个气象站1974～2003年和1个气象站1985～2003年的地面观测资料,统计分析了湄洲湾海雾的天气气候特征.湄洲湾海雾具有明显的年际变化,而且季节差异显著,其中2～5月是海雾的盛季.初步分析了湄洲湾海雾的成因,归纳得出2～5月该海湾海雾生成前的3种环流天气形势:锋面型、入海高压后部型、高压底部型.在对海雾生成的水文气象要素分析的基础上,得出了2～5月海雾发生的一般规律,为海洋预报和服务提供一定的参考依据.